Fluid motor-pump construction

ABSTRACT

A device such a motor or a pump includes a rotatable eccentrically carried member or plate which is connected to rotate one or more radially extending pistons so as to reciprocate them in their associated cylinders for displacing fluid therein, and it includes a slipper pad having a surface on one side which conforms to the curvature of the eccentric plate and is engaged for sliding contact therewith. Each slipper pad engages at its opposite side with a piston member which is radially arranged for reciprocation within its associated cylinder. The piston includes a closed end face adjacent the slipper which conforms to and is maintained in bearing contact with the slipper. Each slipper and associated closed end face of the piston is provided with a communicating passage for permitting the flow of the fluid being pumped into one or more grooves defined on the face of the slipper which is in bearing contact with the cam plate in order to provide lubrication for the bearing sliding contact of the slipper with the cam plate. During the reciprocation of the piston fluid is directed into and out of the associated cylinder through a passage communicating at one end with a distributor valve and which connects at its opposite end into a respective cylinder through a cylinder cap or headpiece arranged at its radial outer end.

United States Patent Kiyoshi Morita Chikushino-machi; Shigemi Kawano, Fukuoka-shi, both of [72] Inventors Dec. 24, 1968, Japan, No. 43/994707 [54] FLUID MOTOR-PUMP CONSTRUCTION 9 Claims, 4 Drawing Figs.

[52] U.S.Cl 91/491, 92/72,91/499,91/488,92/135 [51] 1nt.Cl F01b1/06 [50] FieldofSearch.... 92/72,58, l35;9l/491,488,499

[56] References Cited UNITED STATES PATENTS 3,498,227 3/1970 Yasuo Kita 91/499 3,405,646 10/1968 Thoma 91/499 3,223,046 12/1965 Eickmann 91/488 3,036,557 5/1962 Kimsey.... 92/72 X 2,969,810 l/196l Dudley 91/499 X \M' it R23,993 5/1955 Henrichsen 2,638,850 5/1953 Ferris ABSTRACT: A device such a motor or a pump includes a rotatable eccentrically carried member or plate which is connected to rotate one or more radially extending pistons so as to reciprocate them in their associated cylinders'for displacing fluid therein, and it includes a slipper pad having a surface on one side which conforms to the curvature of the eccentric plate and is engaged for sliding contact therewith. Each slipper pad engages at its opposite side with a piston member which is radially arranged for reciprocation within its associated cylinder. The piston includes a closed end face adjacent the slipper which conforms to and is maintained in bearing contact with the slipper. Each slipper and associated closed end face of the piston is provided with a communicating passage for permitting the flow of the fluid being pumped into one or more grooves defined on the face of the slipper which is in bearing contact with the cam plate in order to provide lubrication for the bearing sliding contact of the slipper with the cam plate. During the reciprocation of the piston fluid is directed into and out of the associated cylinder through a passage communicating at one end with a distributor valve and which connects at its opposite end into a respective cylinder through a cylinder cap or headpiece arranged at its radial outer end.

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INVENTOR Kwosm Mom-n SHIGEHI KHVHNO ATTORNEY FLUID MOTOR-PUMP CONSTRUCTION SUMMARY OF THE INVENTION This invention relates in general to the construction of fluid motors or pumps and in particular to a new and useful radialpiston-type rotary machine such as a motor or pump which is driven by an eccentrically rotatable cam plate which is maintained in bearing contact with a slipper member which rides over its surface and which forms a support for a closed inner radial end of a piston.

The present invention is an improvement over the prior art principally in respect to the construction of a connecting slipper member for supporting a reciprocating piston over a rotary eccentric cam plate and to the construction of a piston member with an end face which is closed at its inner radial end and includes a passage therein which communicates with a passage of the slipper member for the purpose of lubricating the surface of the slipper member in contact with the cam plate. Devices are known at the present time which include pistons which are reciprocated in radial directions by means of an eccentrically mounted cam plate. With such constructions, however, the interior radial end of the piston is constructed as a socket for receiving a ball head of a combination slipper plate and piston rod member which is articulated to the piston through the ball head construction. The pressure exerted on the piston is transmitted through the ball head of the piston member to a slipper pad having an interior surface curved to slidably engage over the rotatably eccentric cam plate. With such a construction the pressure transmission tends to become unstable due to the long distance between the point of application of the force on the piston and that of the cam plate. In addition, the construction does not operate satisfactorily because the piston rod has a tendency to lift off the cam plate because of the variations of oil pressure conditions which occur. In addition the structure is difficult and expensive to manufacture and to operate.

In accordance with the invention, there is provided a machine which is usable as a motor or pump and which includes one or more cylinders which are arranged for reciprocation in radial directions in respect to a rotatable eccentric cam plate. The pistons are slidably fitted in an associated cylinder and they include closed faces at their inner radial ends which bear in recesses of a slipper member having an opposite face which is curved to conform to the curvature of the cam plate and is maintained in sliding engagement therewith. The side of the piston which is in tight sliding contact with the cam plate is provided with grooves which communicate with a passage which extends through the slipper plate and the closed end of the piston to the interior thereof. The passage is provided with an orifice member to permit some passage of fluid from the interior of the piston throughthe passage to the grooves for lubricating the surface of the slipper which is in contact with the cam plate.

Accordingly, it is an object of the invention to provide an improved radial-type pump or motor construction which includes one or more pistons reciprocating in radially arranged cylinders and wherein the inner radial end of the piston is provided with a closed head which is suitably formed to interengage with a correspondingly complementarily formed surface of a slipper member, the slipper member having an opposite face in sliding engagement with an eccentric cam plate which imparts a reciprocation motion thereto, the slipper being provided with grooves, on its surface which contacts the cam plate, which are supplied with fluid from the associated cylinder through passage means defined within the piston and the slipper plate.

A further object of the invention is to provide a rotary pump or motor which includes a plurality of radially arranged cylinders each having a piston slidable therein for reciprocation in a radial direction, said pistons having a closed end in bearing engagement with a slipper member which is maintained in contact with an eccentric cam plate, the cylinder being connected for the supply and delivery of fluid from its outer radial end and the piston and slipper plate having a small passage with throttle means therein for permitting passage for some of the fluid from the interior of the piston to the surface of the slipper which in bearing contact with the cam plate.

A further object of the invention is to provide a device for pumping liquid and/or producing rotary motion which is simple in design, rugged in construction, and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described in preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is an enlarged partial sectional view of a radial piston-type machine constructed in accordance with the prior art;

FIG. 2 is an enlarged axial sectional view of a radial-pistontype machine constructed in accordance with the invention;

FIG. 3 is an enlarged vertical section taken on the lines III- III of FIG. 2; and

FIG. 4 is a view similar to FIG. 3 of another embodiment of the invention.

GENERAL DESCRIPTION OF THE PRIOR ART A conventional radial-type machine has a construction as indicated in FIG. 1 in which each piston 109 is arranged for sliding movement within its associated radially arranged cylinder 103. The piston 109 is articulated to a piston rod 104 which is formed with a ball head which engages within a socket defined at the radial inner end of the piston 109 in the manner of a ball-and-socket joint. The free end of the piston rod 104 is maintained in sliding contact with a cam plate 108 which is eccentrically secured to a main shaft (not shown) The piston 109 is reciprocated by the rotation of the cam plate 108 to cyclically draw in and discharge liquid through a passage (not shown)at the radial outer end thereof. The end face 142 of the piston rod 104 is maintained in sliding contact with the cam plate 108 and this end face is formed with a recess 143. Passages 114 and 115 defined in the piston head and the piston rod, respectively, provide communication between the interior of the cylinder space 103 and the recess 143 at the location of the bearing contact of the rod 104 with the cam plate 108. This ensures that an oil film will be main tained on the sliding face 142 to thereby reduce the coefficient of friction between the cam plate 108 and th piston rod 104.

In this arrangement, the ratio of the diameter of the ball head of the piston rod d to the diameter D of the piston 109 is usually in the range of 0.5 to 0.7 and cannot be increased up to more than I for structural reasons. Consequently, the pressure exerted upon the piston 109 must be borne only by the extremely restricted surface of the spherical head of the piston rod 104. As a result the surface pressure is concentrated onto the central portion of the spherical surface and the maximum surface pressure of the spherical head increases highly with pressure applied thereto. In addition, the recesses of the piston and the associated parts provide complicated structures and are difficult to machine and particularly to ream. Because the sectional area of the piston rod is limited, it is also difficult to impart a sufficient buckling strength thereto. The pressure transmission from the piston head to the slipper plate tends to become unstable because of the long distance between the point of application of the force and that of the cam plate. It is difficult to conduct oil through the passages 103 and 115 defined in the piston and the piston rod, respectively, to the interior recess 143 defined at the inner radial end of the piston rod at the location where its surface 142 contacts the cam plate 108. The sum ofthe pressure prevailing between the cam plate and the end face of the piston and the inertia force due to rotation becomes greater than the force exerted inwardly on the piston when the piston is in the exhaust position. Consequently, the piston tends to become lifted off the cam plate 108 and the phenomenom of beating due to the oil pressure occurs when the piston has come to the intake position. In order to avoid this, it is necessary to provide a back pressure in the exhaust position so that there is a resultant decrease in efficiency. Because of the necessity to provide a relatively large recess 103, the relatively small surface areas at each leg end 143 does not have sufficient mechanical strength to bear the inward force of the piston 109. This leads to unfavorable deformation or oil leakage. Foreign particles such as dust which is included in the oil of the cylinder 103 will cause the abrasion or seizure of the sliding surfaces defined between the cylinder 103 and the piston rod 104 or between the piston rod 104 in the cam plate 108.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in particular the invention embodied therein in FIGS. 2 and 3 includes a casing or housing generally designated 1 having a plurality of cylinders 3 which are arranged radially from the center line of a main shaft 2. In the drawings, only one of the cylinders is shown but a plurality of said cylinders is usually provided. A bearing box 6 is secured to the casing around the shaft 2 and it is provided with bearings 4 and 5 for rotatably supporting the shaft. A shaft seal member 7 arranged in the box provides means for ensuring that the fluid does not escape from the casing. A cam plate 8 is eccentrically secured on the main shaft 2 for rotation therewith.

In accordance with the invention, pistons are slidably fitted in each of the cylinders 3 and are formed at their radially inner ends with closed portions or closed walls having concave outer surfaces providing a bearing engagement for a slipper plate 11, which, in turn has an opposite surface in sliding contact with the surface of the cam plate 8. The piston 3 as indicated includes a ring 10. The slipper plate or pad 11 has a spherical surface on its piston side which engages with the concave recess and the exterior face of the piston 9. If a larger diameter of the spherical surfaces is desired, the piston 9 and the pad 11 may be so dimensioned that the engaging surface between them is positioned outside of the cylinder 3.

As best seen in FIG. 3, the pad 11 is formed with a concave interior surface formed with grooves 13 which extend lengthwise and crosswise and are interconnected with one another. In addition, the slipper pad 11 and the piston 9 are provided with interconnecting passages 14 and 15 respectively with extend radially and enable the fluid in the cylinder 3 to flow freely into the grooves 13.

In accordance with a feature of the construction the passage 14 carries a throttle member 16 such as an orifice member which is tapered toward tb cylinder 3 and has a small opening 16A for controlling the flow of liquid and for catching dust in the fluid which may be fed to the sliding surface.

A spring 17 is located between the piston 9 and a cylinder cap 18 and it biases the slipper pad 1 1 against the cam plate 8. A port 19 is formed in the cylinder cap 18 and it is connected as indicated in FIG. 2 through a passage 20 to a rotary distributor valve 21 for conducting liquid either into or out of the associated cylinder 3. A passage 20 is provided for each cylinder 3 and a distributor valve 21 of any known type is connected to the main shaft so as to rotate therewith. An inlet port 22 and an outlet port 23 for distributing the fluid is provided in the distributor valve 21. Passages 24 and 25 whiclare defined in the distributing valve 21 communicate with the inlet port 22 and the discharge port 23 respectively, and, in turn, with the passage 20. The passage 20 is communicated with either of the passages 24, 25 depending upon the angular position of the distributing valve 21. Radial ball bearings 26 rotatably support the distributing valve 21.

In the modification of the device shown in FIG. 4, there is provided a casing 1' defining one or more cylinders 3 in which a piston 9 is reciprocal in radial directions. A slipper pad 11' is maintained in engagement with an eccentric cam plate 8' as in the other embodiment and it is provided with a concave interior surface arranged in sliding engagement with the cam. In this embodiment the grooves 13' are supplied with a fluid being pumped through passages 14 and 15', respectively. The passage 14 of the piston 9 carries a throttle member 16' to provide a throttling action on the fluid passing from the cylinder space 3' to the groove or recess 13.

The operation of the inventive device is as follows:

As shown in FIG. 2, fluid from the inlet port 22 flows into one of the cylinders 3 through the passages 24, 20 and the opening 19 to urge the associated piston 9 radially inwardly. The piston 9 acts upon the cam plate 8 through the slipper pad 11 to impart a rotating motion to the cam plate and thus to rotate the main shaft 2. At this time, a part of the fluid is lead through the passages 15 and 14 and the opening 16A of the orifice 16 into the grooves 13 to provide a lubrication for reducing the friction between the cam plate 8 and the sliding plate 12 of the slipper pad 11. Foreign particles which would have been included in the fluid are prevented from passing through the opening 16A of the orifice 16 and they tend to gather at an annular slit 16B of wedgelike cross section which is constituted by the tapered end of the orifice 16 and the inner wall of the passage 14. Therefore a clean fluid will be fed to the sliding portions of the slipper pad 1 1.

During this time the piston of one or more of the remaining cylinders is forced outwardly by the cam plate 8, so that the fluid within the associated cylinder 3 is discharged through the passages and finally out of a discharge port 23. The spring 17 maintains a biasing pressure on the slipper pad 11 to the cam plate 8. This spring force acts due to the decrease of the fluid pressure in the cylinder 3 and assures a close contact between the cam plate and the slipper pad 11. It is of course possible to throttle the discharge passage instead of using a spring 17, and to do it in a way such that a sufficient back pressure will exist in the cylinder to prevent separation of the cam plate 8 and the slipper pad 11. This however, will result in a lower efficiency of the motor.

An advantage of the invention construction, is that a large bearing surface of a slipper pad may be employed instead of the smaller bearing surface of a piston rod. The construction permits a smooth and uniform transmission of the force of the piston 9 to the slipper pad 11 and permits a lowering of the maximum surface pressure. The separate design of a slipper pad member 11 makes it possible to construct the relatively low slipper pad with sufficient buckling strength. The decrease of the distance between the engaging points of the piston 9 and the cam plate 8 permits a stable transmission of force therebetween and a simple structure of the transmitting members and an easy machining of the parts. Means are provided, such as the spring 17, to always ensure that the piston 9 is urged in the direction to maintain close contact between the cam plate 8 and the slipper pad 11 so that the phenomon of beating never occurs when the associated cylinder is shifted from the discharge position to the supply position. The grooves 13 which are formed on the contacting surfaces of each of the slipper pad 1 1, the cam plate 8 permit an improved lubrication on the uniform distribution of contacting pressure. The orifice 16 provides not only a throttling function but also provides means for preventing foreign particles from passing through the passages along with the fluid and thus ensures that the cam plate will be maintained free of abrasion or free of particles which may cause seizure. The invention is equally applicable for a motor or a pump.

What is claimed is:

1. A radial piston machine usable as a motor or a pump, comprising a rotatable cam plate, means mounting said cam plate for eccentric rotatable movement, casing means defining at least one cylinder adjacent the periphery of said cam plate and also defining means for circulating the fluid to and from said cylinder, a piston movable in said cylinder and having a closed end adjacent said cam plate with an exterior piston engagement surface, a slipper pad having a first face with a pad engagement surface complementary to and interengaged with said piston engagement surface and being in pivotal sliding contact therewith, said pad having a second opposite face with a cam plate engagement surface in sliding contact with said cam plate, said cam plate engagement surface including a lubricating groove, passage means defined in said pad and in said piston for the passage of the fluid circulated through said cylinder to the groove of said pad to lubricate the pad and said cam plate, and means to bias said piston and said slipper pad toward engagement with said cam plate, said casing means defining a plurality of cylinders each having an associated piston, a main shaft rotatably supported within said casing means, said cylinders extending radially in respect to said main shaft, said cam plate being affixed to said shaft at an eccentric position and being rotatable therewith, said piston engagement surface being concave, said pad first face being convex and interengaging in the concave engagement surface of said piston, said pad second opposite face being concave and complementary to said cam plate peripheral surface, said second opposite face having a plurality of grooves therein in the region of said concave surface, said passage means including an orifice member therein for throttling the flow of fluid therethrough.

2. A radial piston machine, according to claim 1, wherein said orifice member has a tapered end directed toward said cylinder.

3. A radial piston machine, according to claim 1, wherein said piston comprises a hollow cylinder having an opened end facing radially outwardly, said casing means defining a cylinder cap having a fluid flow passage connected into said cylinder.

4. A radial piston machine, according to claim 3, wherein said passage means includes a piston passage defined through the closed end of said piston and a slipper passage defined through said slipper in communication with said piston passage.

5. A radial piston machine, according to claim 4, including a throttle member disposed within said passage means for throttling the flow of fluid therethrough.

6. A radial piston maclne usable as a motor or a pump, comprising a casing defining a plurality of radially extending cylinders each having a fluid passage communicating with the head thereof at the radial outer end thereof, a shaft rotatably supported within said casing centrally of said cylinders, a cam plate head of cylindrical configuration connected to said shaft and eccentrically supported on said shaft for rotation therewith, a piston slidable in each of said cylinders and having a closed end facing toward said cam plate within an exterior convex surface, a slipper pad for each cylinder having a cam plate surface curved to the configuration of said cam plate and in sliding engagement therewith and having a lubricating groove defined thereon, said slipper pad also having a convex piston-engaging surface in pivotal sliding engagement with the concave surface of said piston, and aligned passages defined in said slipper pad and said piston for the passage of said fluid from said cylinder to the groove of said slipper pad for maintaining a lubricating film between said pad and said cam plate.

7. A radial piston machine, according to claim 6, including means for biasing said piston into engagement with said slipper pad to urge said pad into engagement with said cam plate.

8. A radial piston machine, according to claim 7, wherein said biasing means comprises a coil spring disposed between the head of said cylinder and said piston.

9. A radial piston machine, according to claim 8, wherein said piston comprises a cylinder having an opened end facin radia ly outwar ly, said passage means for directing a flur through said cylinder including a rotary distributor valve connected to said shaft and being rotatable therewith and including means for selectively directing fluid through respective passages for each of said cylinders during rotation of said shaft with said cam plate.

lnvni N.- 

1. A radial piston machine usable as a motor or a pump, comprising a rotatable cam plate, means mounting said cam plate for eccentric rotatable movement, casing means defining at least one cylinder adjacent the periphery of said cam plate and also defining means for circulating the fluid to and from said cylinder, a piston movable in said cylinder and having a closed end adjacent said cam plate with an exterior piston engagement surface, a slipper pad having a first face with a pad engagement surface complementary to and interengaged with said piston engagement surface and being in pivotal sliding contact therewith, said pad having a second opposite face with a cam plate engagement surface in sliding contact with said cam plate, said cam plate engagement surface including a lubricating groove, passage means defined in said pad and in said piston for the passage of the fluid circulated through said cylinder to the groove of said pad to lubricate the pad and said cam plate, and means to bias said piston and said slipper pad toward engagement with said cam plate, said casing means defining a plurality of cylinders each having an associated piston, a main shaft rotatably supported within said casing means, said cylinders extending radially in respect to said main shaft, said cam plate being affixed to said shaft at an eccEntric position and being rotatable therewith, said piston engagement surface being concave, said pad first face being convex and interengaging in the concave engagement surface of said piston, said pad second opposite face being concave and complementary to said cam plate peripheral surface, said second opposite face having a plurality of grooves therein in the region of said concave surface, said passage means including an orifice member therein for throttling the flow of fluid therethrough.
 2. A radial piston machine, according to claim 1, wherein said orifice member has a tapered end directed toward said cylinder.
 3. A radial piston machine, according to claim 1, wherein said piston comprises a hollow cylinder having an opened end facing radially outwardly, said casing means defining a cylinder cap having a fluid flow passage connected into said cylinder.
 4. A radial piston machine, according to claim 3, wherein said passage means includes a piston passage defined through the closed end of said piston and a slipper passage defined through said slipper in communication with said piston passage.
 5. A radial piston machine, according to claim 4, including a throttle member disposed within said passage means for throttling the flow of fluid therethrough.
 6. A radial piston machine usable as a motor or a pump, comprising a casing defining a plurality of radially extending cylinders each having a fluid passage communicating with the head thereof at the radial outer end thereof, a shaft rotatably supported within said casing centrally of said cylinders, a cam plate head of cylindrical configuration connected to said shaft and eccentrically supported on said shaft for rotation therewith, a piston slidable in each of said cylinders and having a closed end facing toward said cam plate within an exterior convex surface, a slipper pad for each cylinder having a cam plate surface curved to the configuration of said cam plate and in sliding engagement therewith and having a lubricating groove defined thereon, said slipper pad also having a convex piston-engaging surface in pivotal sliding engagement with the concave surface of said piston, and aligned passages defined in said slipper pad and said piston for the passage of said fluid from said cylinder to the groove of said slipper pad for maintaining a lubricating film between said pad and said cam plate.
 7. A radial piston machine, according to claim 6, including means for biasing said piston into engagement with said slipper pad to urge said pad into engagement with said cam plate.
 8. A radial piston machine, according to claim 7, wherein said biasing means comprises a coil spring disposed between the head of said cylinder and said piston.
 9. A radial piston machine, according to claim 8, wherein said piston comprises a cylinder having an opened end facing radially outwardly, said passage means for directing a fluid through said cylinder including a rotary distributor valve connected to said shaft and being rotatable therewith and including means for selectively directing fluid through respective passages for each of said cylinders during rotation of said shaft with said cam plate. 